1. Field of the Invention
The present invention relates to a vibration correcting device for optically correcting vibration generated in a picked-up image for example by hand shaking, and an image pickup device, an image pickup system, a camera unit and a lens unit provided with such vibration correcting device.
2. Related Background Art
In an image pickup apparatus such as a video camera, automation and multiplication are made in all the functions such as by auto exposure (AE) or auto focusing (AF) in order to enable satisfactory image pickup operation in an easy manner.
Also in consideration of a fact that, with the compactization of the image pickup apparatus and with the increase in the magnification of the optical system, the vibration of the apparatus is a major factor deteriorating the quality of the picked-up image, there have recently been proposed various vibration correcting functions for correcting the vibration generated in the picked-up image by the vibration of such apparatus (namely vibration in the supporting hand). A further satisfactory image pickup operation can be easily achieved by providing the image pickup apparatus with such vibration correcting function.
As the vibration correcting function adapted for use in an image pickup apparatus for obtaining a picked-up image by focusing the light from the object on the image pickup face of an image pickup element, there is known a configuration as shown in FIG. 11.
In such vibration correcting function 600, an angular velocity detection sensor 601 is composed of an angular velocity sensor such as a vibration gyro, and, being mounted on the main body of the image pickup apparatus, detects the vibration thereof as an angular velocity.
A DC cut-off filter 602 cuts off the DC component of an angular velocity signal outputted from the angular velocity detection sensor 601 and only transmits the AC component, that is, the vibration component.
An amplifier 603 amplifies the angular velocity signal from the DC cut-off filter 602 to an appropriate sensitivity level.
An analog/digital (A/D) converter 604 digitizes the angular velocity signal outputted from the amplifier 603.
A high-pass filter (HPF) 605, an integrator 606 and a pan/tilt discrimination circuit 607 are composed for example of a microcomputer COM.
The high-pass filter 605 can variably change characteristics thereof with an arbitrary frequency range, and outputs the digital angular velocity signal (angular velocity data) from the A/D converter 604 after cutting off the low frequency component contained therein.
The integrator 606 can variably change characteristics thereof with an arbitrary frequency range, and, integrating the angular velocity data from the high-pass filter 605, outputs the result of integration as angular displacement data.
The pan/tilt discrimination circuit 607 executes panning control by discriminating panning/tilting based on the angular velocity data from the A/D converter 604 and the angular displacement data from the integrator 606.
More specifically, if the angular velocity data is at least equal to a predetermined threshold value, or if it is less than the predetermined threshold value but the angular displacement data (result of integration) is at least equal to a predetermined threshold value, a panning or tilting state is identified and the panning control is executed. In such panning control, the low range cut-off frequency of the high-pass filter 605 is shifted to a higher frequency, whereby a vibration correcting system in an image correction device 610 does not respond to lower frequencies. Also the time constant employed in the integrating operation of the integrator 605 is shifted to a shorter time, whereby the vibration correcting position of the image correcting circuit 610 is gradually shifted toward the center of a movable range and the angular displacement data outputted from the integrator 606 gradually approached a reference value (a value to be assumed in the absence of vibration).
In other situations, the panning or tilting is identified to have been completed, and the low range cut-off frequency of the high-pass filter 605 is shifted to a lower frequency and the time constant employed in the integrating operation of the integrator 606 is shifted to a longer time. Thus the low range cut-off frequency of the high-pass filter 605 and the time constant employed in the integrating operation of the integrator 606 are returned to the original state, and the panning control is terminated.
A digital/analog (D/A) converter 608 converts the angular displacement data from the integrator 606 into an analog value.
A driving circuit 609 drives the image correction device 610 based on the analog angular displacement data outputted from the D/A converter 608.
The image correction device 610 is provided with an optical vibration correcting unit employing, for example a variable angle prism, and varies the vertical angle of the variable angle prism according to the drive by the drive circuit 609, thereby optically correcting the vibration generated in the picked-up image.
As explained in the foregoing, the vibration correcting function 600 is adapted to detect the vibration in the apparatus by the angular velocity detection sensor 601 employing for example the vibration gyro, and to optically correct the vibration in the picked-up image based on the result of such detection.
However, the conventional vibration correcting functions such as that 600 have been associated with the following drawbacks:
(1) In a configuration for correcting the vibration in the picked-up image, utilizing the output signal of the vibration gyro or the like detecting the angular velocity, the error in the correction of the picked-up image increases with an increase in the magnification of the image pickup lens, namely when the image pickup lens is operated at a telephoto side.
The error in the correction of the picked-up image indicates insufficient or excessive correction in the vibration correction system with respect to the vibration amount in the main body of the apparatus. The amount of correction error on the image pickup plane increases with an increase in the focal length of the optical system of the image pickup apparatus, which results in an increase in the image magnification.
(2) On the other hand, there is proposed a video camera with an interchangeable lens system similar to the conventional still camera, in order to widen the image pickup applications of the video camera.
In such a video camera, the interchangeable lens system allows one to easily attach a lens of high magnification, since such a high-magnification lens or an extender can be detachably mounted.
Consequently, the above-described correction error becomes larger in the image pickup apparatus of the interchangeable lens system such as the video camera, in comparison with the image pickup apparatus with the fixed lens.
(3) In particular, in the angular velocity detecting sensor utilizing the vibration gyro, the detection characteristics thereof deteriorate in a low frequency region less than 1 Hz. Consequently, in such low frequency region, the above-described correction error increases evidently, showing an insufficient correction in the low frequency region and leading to deterioration of the image quality.
In order to solve these drawbacks, there is proposed a vibration correcting function with improved correcting performance, by providing a circuit for detecting the remnant or insufficient vibration in the picked-up image, in addition to the angular velocity detection sensor employing for example the vibration gyro.
For example, as shown in FIG. 12, such vibration correction function 700 is provided, in addition to the components 601-610 of the vibration correction function 600 shown in FIG. 11, with a camera signal processing circuit 701 for generating a video signal for example of the NTSC format from the image information obtained from the image pickup element of the image pickup apparatus, a motion vector detection circuit 702 for detecting a motion vector of the image based on the luminance signal contained in the image signal generated in the camera signal processing circuit 701, and a high-pass filter 605xe2x80x2, an integrator 606xe2x80x2 and a pan/tilt discrimination circuit 607xe2x80x2 for converting the motion vector detected by the motion vector detection circuit 702 into a displacement amount (displacement data).
The high-pass filter 605xe2x80x2, the integrator 606xe2x80x2 and the pan/tilt discrimination circuit 607xe2x80x2 are composed of a microcomputer COMxe2x80x2, like the aforementioned microcomputer COM, and thereby the panning/tilting is discriminated and the panning control is executed based on the motion vector outputted from the motion vector detection circuit 702 and the displacement data of the motion vector outputted from the integrator 606xe2x80x2.
The vibration correcting function 700 is further provided with an adder 703 for adding the angular displacement data outputted from the integrator 606 of the microcomputer COM and the displacement data of the motion vector outputted from the integrator 606xe2x80x2 of the microcomputer COMxe2x80x2, and the result of addition in the adder 703 is supplied to a D/A converter 608.
In the above-described configuration, therefore, the displacement amount of the motion vector of the picked-up image, namely the remnant vibration therein, is added to the angular displacement amount as auxiliary information thereof, and the vibration in the picked-up image is optically corrected. As a result, the correction of vibration can be achieved with higher accuracy.
However, such conventional vibration correcting function has still been associated with the following drawbacks.
The angular velocity data obtained from the output of the angular velocity detection sensor 601 and the motion vector obtained from the motion vector detection circuit 702 are related in a complex manner with the panning control in the microcomputers COM, COMxe2x80x2, and sufficient correction of vibration may not be achieved in certain cases.
As a specific example, in case the output of the integrator 606 of the angular velocity detection sensor 601 increases alone, the panning control is executed even when the output of the integrator 606xe2x80x2 of the motion vector detection circuit 702 is close to xe2x80x9c0xe2x80x9d, and the correction of vibration by the output of the motion vector detection circuit 702 is not executed. Similarly, in case the output of the integrator 606xe2x80x2 of the motion vector detection circuit 702 increases alone, the correction of vibration by the output of the angular velocity detection sensor 601 is not executed.
In particular, as the vibration in the picked-up image is corrected according to the angular displacement information (vibration information) obtained from the output of the angular velocity detection sensor 601 utilizing the vibration gyro and the displacement amount (vibration information) of the motion vector obtained from the output of the motion vector detection circuit 702, the correction by the motion vector detection circuit 702 has a larger weight in the low frequency region of 1 Hz or less where the detection characteristics of the vibration gyro become inferior. Consequently, in such configuration, the panning control is executed with emphasis on either of the angular velocity detection sensor 601 and the motion vector detection circuit 702, whereby the correcting function becomes deteriorated.
In consideration of the foregoing, an object of the present invention is to provide a vibration correcting device capable of effecting smooth control for correcting the vibration in the picked-up image with a simple configuration, thereby achieving improvement in the correcting performance.
Another object of the present invention is to provide an image pickup apparatus, an image pickup system, a camera unit and a lens unit provided with a smooth vibration correcting function of high performance.
The above-mentioned objects can be attained, according to a preferred embodiment of the present invention, by providing a vibration correcting device comprising first vibration correcting amount output means for obtaining and outputting a vibration correcting amount from the amount of vibration of the apparatus, second vibration correcting amount output means for obtaining and outputting a vibration correcting amount from the amount of vibration in a picked-up image obtained by picking up an object image with image pickup means through an optical system, correction means for correcting the vibration in the picked-up image based on the output of the first and second vibration correcting amount output means, and control means for controlling the outputs of the first and second vibration correcting amount output means based on the outputs thereof.
According to another preferred embodiment of the present invention, there are provided an image pickup apparatus, a camera, a lens unit and an image pickup system capable of optimum correction of vibration with vibration correcting means of different systems.
Still other objects of the present invention, and the features thereof, will become fully apparent from the following description which is to be picked-up in conjunction with the attached drawings.